The present invention relates to an ink wastage absorber and an ink supporter capable of improving the absorptivity for pigment ink or dye ink.
In recent years, along with the widespread use of personal computers, various kinds of printers have been available. The printing mechanism of these printers has been recently shifted from the wire-dot mode or ink-ribbon mode to the laser mode or ink-jet mode. In particular, the ink-jet mode lower in cost than the laser mode has been widely used. Dye ink has been generally used for the ink-jet type printer; however, along with the recent trend toward color printing, pigment ink has come to be used.
In the ink-jet type printer, excess ink which is accumulated in the printer by cleaning a printer head may flow therefrom and contaminate a portion near the printer head. To cope with such an inconvenience, an ink absorbing member for absorbing excess ink is laid at a portion corresponding to the printer head.
The ink absorbing has been initially made from non-woven fabric of pulps or fibers; however, since it has presented a problem associated with scattering of fibers due to fuzzing, a flexible polyurethane foam has recently come to be widely used. Along with the shifting from dye ink to pigment ink, attempts have been made to improve the ink absorptivity of the flexible polyurethane foam. In particular, since pigment ink is used in a state in which fine particles of, for example, a carbon as a pigment are dispersed in a solvent, it is different in ink absorptivity from dye ink. And, the conventional ink absorbing member may be clogged with particles of carbon or the like, thereby failing to sufficiently achieve the absorbing ability thereof.
Further, along with the demand toward the miniaturization and lightweightness of a printer, it becomes difficult to lay the ink absorbing member at a position being directly in correspondence with a printer head. To solve such a problem, there is adopted a method of laying the ink absorbing member at a position slightly separated from a printer head, and connecting the ink absorbing member to the printer head by means of an ink permeation member having a good ink absorptivity. In view of the foregoing, it is expected to provide an ink wastage absorber used as an ink permeation member or an ink absorbing member, which is further improved in its performance.
An object of the present invention is to provide an ink wastage absorber having a good ability of absorbing dye ink or pigment ink, and a production process thereof.
Another object of the present invention is to provide an ink supporter including an ink permeation member and an ink absorbing member.
To achieve the above object, according to a first aspect of the present invention, there is provided an ink wastage absorber made from a flexible polyurethane foam having an air-permeability of 1.0 cc/cm2/sec or more.
According to a second aspect of the present invention, there is provided an ink wastage absorber having a good ink absorptivity, which is made from a flexible polyurethane foam produced by using a foamable raw material for flexible polyurethane foam containing a polyol, an isocyanate, a catalyst, and a foaming agent, wherein the flexible polyurethane foam is impregnated with a surface active agent. The surface active agent is preferably sodium succinate.
According to a third aspect of the present invention, there is provided a process of producing an ink wastage absorber having a good ink absorptivity, which includes the steps of: preparing a flexible polyurethane foam by using a foamable raw material for flexible polyurethane foam containing a polyol, an isocyanate, a catalyst, and a foaming agent, and compressing the flexible polyurethane foam as needed; dipping the flexible polyurethane foam or the compressed foam in water in which a surface active agent is dispersed; and squeezing water from the flexible polyurethane foam thus treated and then drying the flexible polyurethane foam, to make the surface active agent adhere on the surface of the flexible polyurethane foam.
The ink wastage absorber can be applied to any one of the ink permeation member or the ink absorbing member provided at a portion corresponding to a printer head, or the ink absorbing member being in contact with the ink permeation member.
The ink wastage absorber of the present invention has a good ink (particularly, pigment ink) absorptivity, which is equal to or more than that of the existing ink absorbing member made from pulps or felts. The ink absorbing member made from pulps or felts is intended to improve the ink absorptivity by making use of the pillar phenomenon; however, if such an ink absorbing member is used for absorption of pigment ink, it may be clogged with particles of, for example, carbon as a pigment component, with a result that the absorbing ability of the member be significantly degraded.
To cope with such an inconvenience, the ink absorbing member is required to have an ability of readily absorbing and supporting pigment ink, and further the ink permeation member as a bridging member to the ink absorbing member must be smaller in pillar effect than the ink absorbing member for preventing the occurrence of clogging of ink upon drying (upon no use of the member) or a failure in absorption. In view of the foregoing, the ink wastage absorber of the present invention is intended to improve the absorptivity for pigment ink by impregnating a surface active agent in the main body of the ink wastage absorber.
According to a fourth aspect of the present invention, there is provided an ink supporter including: an ink permeation member provided at a portion corresponding to a printer head, the ink permeation member being obtained by producing a flexible polyurethane foam by using a foamable raw material for flexible polyurethane foam containing a polyol, an isocyanate, a catalyst, and a foaming agent, and making the flexible polyurethane foam contain a surface active agent; and an ink absorbing member being in contact with the ink permeation member, the ink absorbing member being obtained by producing a flexible polyurethane foam by using a foamable raw material containing a polyol, an isocyanate, a catalyst, and a foaming agent, and thermally compressing the flexible polyurethane foam at a compression magnification of 2 to 20 times by a hot press. The ink absorbing member preferably contains a surface active agent.
The ink supporter having the above configuration exhibits a feature capable of readily absorbing and supporting ink, particularly, pigment ink. To be more specific, if the ink permeation member provided at a portion corresponding to a printer head is formed of an absorbing member having a good ink absorptivity due to the capillary phenomenon, which is obtained by hot-pressing a flexible polyurethane foam, such an ink permeation member may be clogged with particles of, for example, carbon as a pigment component, with a result that absorbing ability be significantly degraded.
Accordingly, the ink permeation member requires the ability of readily absorbing and supporting pigment ink, and also it must be lower in capillary effect than the ink absorbing member as a main body for preventing the occurrence of clogging of ink upon drying (upon no use of the member) and a failure in absorption. For this reason, according to the present invention, the flexible polyurethane foam for forming the ink permeation member is impregnated with a surface active agent for improving the absorptivity for pigment ink.
On the other hand, the ink absorbing member is thermally compressed, and is preferably made to contain a surface active agent, to thereby ensure a good ink absorptivity as well as a good ink supporting ability.
The present invention provides an ink supporter including an ink permeation member provided at a portion corresponding to a printer head and an ink absorbing member being in contact with the ink permeation member, wherein ink which has flowed out of a printer head permeates in the ink permeation member, being absorbed in the ink absorbing member through the ink permeation member, and is supported by the ink absorbing member.
The present invention also provides an ink wastage absorber. According to the present invention, the wording xe2x80x9can ink wastage absorberxe2x80x9d includes the above ink absorbing member and the above ink permeation member. It should be noted that the ink absorbing member can be used in the state being directly in correspondence with a printer head as needed, and in this case, the use of the ink permeation member is omitted.
Each of the above ink permeation member and the ink absorbing member is made from a flexible polyurethane foam produced by using a foamable raw material for flexible polyurethane foam containing a polyol, an isocyanate, a catalyst, a foaming adjusting agent, and a foaming agent.
As the polyol, there is preferably used poly-(oxyethylene-oxyalkylene) polyetherpolyol in which ethylene oxide and an alkylene oxide component other than ethylene oxide are added to an active hydrogen-containing compound having two or more functional groups. Here, examples of the alkylene oxide components include propylene oxide, butylene oxide, and styrene oxide; and examples of the active hydrogen-containing compound used for producing the above polyol include a polyalcohol and a polyamine. Examples of the polyalcohols include ethylene glycol, propylene glycol, glycerine, trimethylol propane, 1,2,6-hexane triol, pentaerythritol, sorbitol, and saccharose.
According to the present invention, a metal salt of an organic acid having a hydrophilic property may be blended to a polyol generally used for producing a flexible polyurethane foam. As the metal for the metal salt of an organic acid, there may be effectively used potassium, sodium, magnesium, tin, copper, lithium, or silver, preferably, potassium or sodium.
The organic isocyanate used for reaction with the polyol is not particularly limited but may be toluenediiusocyanate, phenylenediisocyanate, diphenylmethanediisocyanate, or 4,4xe2x80x2-diphenyldiisocyanate. Of these isocyanates, a mixture of a 2,4-isomer and a 2,6-isomer of toluenediisocyanate at a mixing ratio of 80:20 or 65:35 is preferably used in terms of economy. The amount of the organic isocyanate to the total amount of the polyol and the other active hydrogen-containing compound, that is, the isocyanate index may be in a range of 80 to 130, preferably, 100 to 110.
As the catalyst, there is used an organic tin compound catalyst or an amine based catalyst. Examples of the organic tin compound catalysts include stannous octoate, stannous oleate, dibutylditinlaurate, dibutyltindi-2-ethylhexoate, and dibutyltindiacetate. Examples of the amine based catalysts include generally used amine based catalysts, for example, triethylamine, triethylenediamine, N-ethylmorpholine, dimethylethanolamine, dimethylbenzylamine, 1,8-diazabicyclo(5.4.0)undecene-7 and its phenol salt, and triethylenediamine formate. These catalysts may be used singly or in combination of two kinds or more. In addition. as the amine based catalyst suitable for the flexible polyurethane foam of the present invention, there is generally used an amine based catalyst which is generally used for forming a flexible polyurethane foam; however, an amine based catalyst having a reactivity is preferably used for an application with a problem associated with elution or the like. The content of the catalyst is not particularly limited but may be generally in a range of 0.005 to 2 parts by weight on the basis of the 100 parts by weight of the polyol.
As the foaming adjusting agent, there is used a silicone surfactant generally used for forming a flexible polyurethane foam; however, a foaming adjusting agent having a reactivity may be preferably used for an application with a problem associated with elution or the like. The content of the foaming adjusting agent is set in a range of 0.1 to 3.0 parts by weight, preferably, 0.5 to 2.0 parts by weight on the basis of 100 parts by weight of the polyol.
As the foaming agent, there is used water, methylene chloride, or a volatile liquid having a low boiling point.
To satisfy the performance required for the flexible polyurethane foam, in addition to the above-described components, a filler, an antistatic agent, a coloring agent, or a flame retarder may be added to the flexible polyurethane foam without departing from the scope of the present invention.
If the flexible polyurethane foam requires a higher hardness, a cross linking agent or the like may be of course added to the foamable raw material for increasing the hardness thereof.
The flexible polyurethane foam can be produced from the above-described foamable raw material in accordance with a known process.
The density of the flexible polyurethane foam is set in a range of 0.005 to 0.150 g/cm3, preferably, 0.01 to 0.05 g/cm3, and the number of cells of the polyurethane foam is set in a range of 40 to 150 pieces/25 mm, preferably, 60 to 150 pieces/25 mm. To be more specific, in the case of using the flexible polyurethane foam in the compressed state, the number of cells of the polyurethane foam is set in a range of 20 to 150 pieces/25 mm, preferably, 40 to 150 pieces/25 mm.
According to the first aspect of the present invention, the flexible polyurethane foam, which may be used either in the non-compressed state or in the compressed state, is characterized in that the air-permeability thereof is in a range of 1.0 or more, preferably, 5.0 to 300, more preferably, 10 to 300, most preferably, 20 to 300 cc/cm2/sec.
The flexible polyurethane foam having an air-permeability less than 1.0 cc/cm2/sec is poor in its ink absorbing performance, and therefore, it cannot achieve the object of the present invention. It should be noted that the above air-permeability is measured by the method specified under JIS L 1004.
The density, the number of cells, the diameter of each cell, and a porosity of the flexible polyurethane foam having the above air-permeability can be suitably selected; however, it is effective to use the reticulated flexible polyurethane foam with no cell membranes. The reticulated flexible polyurethane foam with no cell membranes can be produced in accordance with a process of preparing a flexible polyurethane foam with cell membranes by a usual manner, and removing the cell membranes, or a process of producing a flexible polyurethane foam by a manner not to form cell membranes.
The flexible polyurethane foam is, as described above, used either in the non-compressed foam or in the compressed foam. In this case, the compression magnification is set in a range of 1 to 20 times. The state in which the compression magnification is one time means the non-compressed state. Accordingly, the compressed foam may be obtained by slightly compressing the non-compressed foam; however, in general, it is obtained by compressing the non-compressed foam at a compression magnification ranging from 2 to 20, preferably, 5 to 10, more preferably, 8 to 10 times. The compression of the polyurethane foam is not particularly limited but may be generally performed by a hot-press process. The hot-press process includes the steps of compressing the flexible polyurethane foam at a specific magnification by hot platens heated at a temperature of about 150 to 240xc2x0 C., and keeping such a state until the compressed state is fixed at the compression magnification. The hot-press time is not particularly limited but may be generally set in a range of 2 to 20 min.
With respect to the compressed flexible polyurethane foam, as the compression magnification becomes larger, the capillary effect becomes larger, but the density becomes high and thereby the ink supporting ability becomes lower. Accordingly, in practical use of the polyurethane foam, the density and the compression magnification thereof must be set with a good balance kept therebetween. For example, the ink absorbing member being in contact with the ink permeation member is required to be made higher in capillary effect (that is, ink suction rate and ink suction height) than the ink permeation member, and further the ink absorbing member is required to ensure a sufficient ink absorbing capacity and to prevent occurrence of clogging of ink and a failure in absorption. In consideration of these conditions, the number of cells, the compression magnification, and the air-permeability of the polyurethane foam used for the ink absorbing member must be selected.
In the case of using the ink wastage absorber of the present invention as the ink absorbing member being in contact with the ink permeation member, the ink wastage absorber may be made from a plurality of layers different in air-permeability, wherein the plurality of layers are stacked such that the ink absorptivity becomes higher at a position closer to the ink absorbing side and the ink supporting ability becomes higher at a position farther from the ink absorbing side, that is, the air-permeability on the ink absorber side is low and becomes gradually higher at a position farther from the ink absorbing side.
The formation of the plurality of layers may be concretely performed by stacking two to six layers, particularly, three to five layers different in compression magnification and/or number of cells. Further, to form a plurality of layers different in compression magnification and/or number of cells, the hot- compression may be made in a state In which the hot-platen is pressed on only one surface of the foam.
The ink absorptivity of the ink wastage absorber can be enhanced by slitting the surface, on the ink absorbing side, of the ink wastage absorber. To be more specific, the slits, spaced at intervals of 2 to 50 mm, particularly, 5 to 10 mm, are provided in parallel or in a grid pattern.
According to the present invention, a surface active agent can be impregnated in or made to adhere on the above-described flexible polyurethane foam (non-compressed foam or compressed foam) for further improving the ink absorptivity.
As the surface active agent, there is used an anionic surface active agent such as ethylene oxide, an alkali salt of higher fatty acid, or alkylsulfonate; a cationic surface active agent such as a higher amine haloganate, or a quaternary ammonium salt; a nonionic surface active agent such as polyethyleneglycolalkylether, or sorbitan fatty acid ester; or an amphoteric surface active agent such as amino acid. In particular, a denaturated sodium succinate is preferable in terms of effect. According to the present invention, as the denaturated sodium succinate, there is preferably used sodium dialkylestersulfosuccinate expressed by the following expression: 
where R is an alkyl group or aralkyl group having the carbon number of 1 to 18.
Examples of the esters include di-n-amyl, di-n-hexyl, di-n-heptyl, di-n-octyl, di-n-nonyl, monoethylmonododecyl, monobutylmonododecyl, mono-2-ethylhexyl-mono-1-methylbenzyl, mono-2-ethylhexyl-mono-1-methyl-4-ethylhexyl, di-1-methylbutyl, di-2-methylbutyl, di-isoamyl, di-1,3-dimethylbutyl, di-1-methylamyl, di-dimethylamyl, di-1-isopropylisobutyl, di-1-propylbutyl, di-1-methylhexyl, di-2-ethylhexyl, di-1-methylheptyl, di-1-butylamyl, di-1-isobutyl-3-methylbutyl, di-1-methyl-4-ethylhexyl, and di-1-methyl-4-ethyloctyl.
Such a surface active agent may be of a water-soluble type. This is because if a water-soluble surface active agent is used, the polyurethane foam may be only dried after being impregnated with the water-soluble type surface active agent. The content of the surface active agent differs depending on the required performance of the flexible polyurethane foam. However, in the case of using the denaturated sodium succinate as the surface active agent, the content thereof is set in a range of 1 to 500,000 g, preferably, 1,000 to 20,000 g per 1 m3 of the flexible polyurethane foam.
The surface active agent can be made to adhere on the flexible polyurethane foam by a process of dipping the non-compressed or compressed foam in water in which the surface active agent has been dispersed or dissolved, squeezing the water from the non-compressed or compressed foam thus treated, and drying the non-compressed or compressed foam.
The ink wastage absorber of the present invention configured as described above has effects that the absorber has an ability of uniformly, accurately absorbing a large amount of ink, and the absorber is usable in a state being cut into a shape matched to a complicated set-up position in a printer and thereby can be made low in cost, and that since the absorber is made from the flexible polyurethane foam, it can eliminate the occurrence of the fuzzing of felts or the like and also eliminate the occurrence of the inconvenience that the function of the printer is affected by feathers fallen in the printer.
The ink supporter of the present invention configured as described above has effects that the ink absorbing performance is not degraded after the ink is dried, and even if ink overflows, the ink is reabsorbed from an introducing portion, that is, the ink can be perfectly absorbed, and that the ink absorbing rate in the vertical direction can be adjusted, as needed, by providing slits or pins in or on the ink supporter in the vertical direction.